WO2019144491A1 - 一种压铸铝零件表面处理工艺 - Google Patents

一种压铸铝零件表面处理工艺 Download PDF

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WO2019144491A1
WO2019144491A1 PCT/CN2018/080469 CN2018080469W WO2019144491A1 WO 2019144491 A1 WO2019144491 A1 WO 2019144491A1 CN 2018080469 W CN2018080469 W CN 2018080469W WO 2019144491 A1 WO2019144491 A1 WO 2019144491A1
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die
cast aluminum
nickel
aluminum parts
layer
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PCT/CN2018/080469
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English (en)
French (fr)
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简开宇
杨前曾
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宁波沈鑫电子有限公司
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/1601—Process or apparatus
    • C23C18/1633—Process of electroless plating
    • C23C18/1689—After-treatment
    • C23C18/1692—Heat-treatment
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C12/00—Solid state diffusion of at least one non-metal element other than silicon and at least one metal element or silicon into metallic material surfaces
    • C23C12/02—Diffusion in one step
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/18—Pretreatment of the material to be coated
    • C23C18/1803—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces
    • C23C18/1806—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces by mechanical pretreatment, e.g. grinding, sanding
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/18—Pretreatment of the material to be coated
    • C23C18/1803—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces
    • C23C18/1824—Pretreatment of the material to be coated of metallic material surfaces or of a non-specific material surfaces by chemical pretreatment
    • C23C18/1837—Multistep pretreatment
    • C23C18/1844—Multistep pretreatment with use of organic or inorganic compounds other than metals, first
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/31—Coating with metals
    • C23C18/32—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron
    • C23C18/34—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron using reducing agents
    • C23C18/36—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron using reducing agents using hypophosphites
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/32—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer
    • C23C28/322—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer only coatings of metal elements only
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
    • C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/1601—Process or apparatus
    • C23C18/1633—Process of electroless plating
    • C23C18/1646—Characteristics of the product obtained
    • C23C18/165—Multilayered product
    • C23C18/1653—Two or more layers with at least one layer obtained by electroless plating and one layer obtained by electroplating

Definitions

  • the invention belongs to the technical field of metal surface treatment, in particular to a surface treatment process of die-cast aluminum parts.
  • inorganic chromium-free treatment methods mainly use zirconium, titanium, cobalt, Metal inorganic salts such as molybdenum and rare earth are used as the main salt of the film forming solution to form a thin conversion film on the surface of the aluminum alloy; the organic film treatment method can improve the adhesion between the polymer and the inorganic material by using the organosilane.
  • An organic protective film is formed on the surface of the metal, but the film formation time of the organic film is long and the cost is high.
  • the surface of the aluminum and aluminum alloy materials after the surface treatment is easily reacted with oxygen in the air to affect the surface treatment effect in the later stage, and the prior art generally adopts a zinc coating layer on the surface of the aluminum and aluminum alloy materials.
  • the aluminum and aluminum alloy surfaces are prevented from being oxidized and the bonding with the surface treatment layer is improved by partially sacrificing this zinc-coated layer.
  • the zinc-coated layer is basically discharged as a waste liquid at the end, which not only causes environmental pollution, but also increases the cost of surface treatment of aluminum and aluminum alloy.
  • the object of the present invention is to provide a surface treatment process for die-cast aluminum parts, so as to solve the problem that the surface bonding of the die-cast aluminum has low bonding force and high processing cost.
  • a surface treatment process for die-cast aluminum parts comprising the following steps:
  • step 2) subjecting the die-cast aluminum parts of step 2) to a nickel plating pretreatment process
  • the blasting treatment is ceramic blasting, and the surface roughness of the die-cast aluminum parts is controlled to be 40-60 ⁇ m.
  • the method for preparing nickel on the surface of the die-cast aluminum part and forming a surface aluminum nitride layer is
  • the processed die-cast aluminum parts are sealed, and the sealed die-cast aluminum parts are buried in a mixture of nickel nitride and carbon, heated to 350 ° C -380 ° C under a nitrogen atmosphere of 0.3-1 MPa, and kept at 0.5-2. Hours, then to room temperature;
  • the mass ratio of the nickel nitride to the carbon is 1:10-1:5.
  • the nickel plating pretreatment step includes at least a cleaning step and a pickling step, and further includes an alkali liquid neutralization step and a deionized water rinse step after the pickling step.
  • the washing step includes an alkali liquid degreasing step, an ultrasonic cleaning step, an alkali liquid degreasing, and an ultrasonic cleaning step.
  • the alkaline electroless nickel plating solution is calculated by weight percentage, and its composition is:
  • the protective layer is a chromium-free protective layer or a chromium-containing protective layer.
  • the surface treatment process of the die-casting aluminum of the technical solution firstly performs surface nickel plating and surface aluminum nitride layer treatment before the nickel plating layer is performed, so that nickel is infiltrated between the gaps of the die-cast aluminum parts by a nickel infiltration process, and then An aluminum nitride protective layer is formed by nitrogen and aluminum on the surface of the die-cast aluminum part, which can prevent oxidation reaction between aluminum and oxygen, and can improve the bonding force between the nickel plating layer and the die-cast aluminum surface, and at the same time, avoid The use of zinc in the die-cast aluminum surface treatment process reduces processing costs.
  • the technical solution provides a surface treatment process for die-cast aluminum parts, comprising the following steps:
  • the die-cast aluminum parts are subjected to sand blasting; in the present application, the ceramic blasting treatment technology is used, and the surface roughness of the die-cast aluminum parts is controlled to be 40-60 ⁇ m.
  • the ceramic used in the present application is an alumina ceramic to prevent the infiltration of elements such as silicon and iron during the sand blasting process due to the action of pressure. It affects the final treatment effect on the surface of die-cast aluminum parts, especially the bonding force between the nickel plating layer and the surface of the die-cast aluminum parts.
  • step 2) subjecting the die-cast aluminum parts of step 2) to a nickel plating pretreatment process
  • the die-cast aluminum parts after the pre-treatment process are plated with a nickel-plated layer in the alkaline electroless nickel plating solution; the processed die-cast aluminum parts are sealed, and the sealed die-cast aluminum is sealed.
  • the parts were buried in a mixture of nickel nitride and carbon, heated to a temperature of 350 ° C to 380 ° C under a nitrogen atmosphere of 0.3-1 MPa, and held for 0.5-2 hours, and then cooled to room temperature.
  • the mass ratio of nickel nitride to carbon is 1:10-1:5.
  • nickel nitride is decomposed into nitrogen and metallic nickel at 350 ° C to 380 ° C.
  • metallic nickel in contact with the surface of the die-cast aluminum part penetrates into the surface of the die-cast aluminum part, and at this temperature, Carbon does not penetrate into the surface of die-cast aluminum parts and does not react with aluminum on the surface of die-cast aluminum parts to form aluminum carbide, which affects the subsequent processing.
  • the nickel layer covers quickly, and the pores on the surface of the die-cast aluminum part are covered by the nickel plating layer instead of being filled, that is, in the prior art nickel plating process, the die-cast aluminum part
  • the pores of the surface are not filled, but only covered, so that the pores after nickel plating on the surface of the die-cast aluminum part are still present, and some of the pores have water molecules in the plating solution, so that the pores exist in the pores.
  • the formation of chemical batteries affects the corrosion resistance of die-cast aluminum parts.
  • the technical solution is to infiltrate into the gap of the die-cast aluminum part by the infiltration method before the nickel plating layer is carried out, and fill the pores of the die-cast aluminum part, which is also the prior art even if the zinc coating is carried out.
  • the layer also does not solve the problem of voids on the surface of die-cast aluminum parts, and does not require the use of a sacrificial layer of zinc coating.
  • the technical scheme is to use an automatic wire drawing machine to pull the silk thread on the nickel plating layer on the side of the die-cast aluminum part to improve the quality of the die-cast aluminum part.
  • the nickel plating pretreatment step includes at least a cleaning step and a pickling step, and further includes an alkali liquid neutralization step and a deionized water rinse step after the pickling step.
  • the cleaning process includes an alkali liquid degreasing process, an ultrasonic cleaning process, or an alkali liquid degreasing and ultrasonic cleaning process.
  • the pre-treatment process before nickel plating is prior art, and the applicant does not describe in detail herein. Any pre-treatment process that can be applied to the prior art can be applied in the present technical solution.
  • Alkaline electroless nickel plating solution calculated by weight percentage, consisting of:
  • the pH of the electroless nickel plating solution is 8.0-9.0.
  • the protective layer is a chromium-free protective layer or a chromium-containing protective layer.
  • the nickel-plating treatment technology before the nickel plating layer and the formation of the aluminum nitride layer the technology for the last protective layer is prior art, and the prior art can be used as needed.
  • the chrome-free treatment technology or the chrome treatment technology can be used, and does not affect the realization of the technical solution of the present application.
  • the differences of the respective embodiments are respectively the treatment of the surface nickel plating and the surface aluminum nitride layer and the alkaline electroless nickel plating solution.
  • the method for preparing nickel on the surface of die-cast aluminum parts and forming a surface aluminum nitride layer is
  • the processed die-cast aluminum parts are sealed, and the sealed die-cast aluminum parts are buried in a mixture of nickel nitride and carbon, heated to 350 ° C under a nitrogen atmosphere of 0.3 MPa, and kept for 0.5 hours, and then cooled to room temperature. ;
  • the mass ratio of nickel nitride to carbon is 1:5.
  • Alkaline electroless nickel plating solution calculated by weight percentage, consisting of:
  • NaCL12.6H 2 O is 8%; NiSO 4 .6H 2 O is 10%; NaHPO 2 .2H 2 O is 9%; (NH 4 ) 3 C 6 H 5 O 7 is 20%; complexing agent is 20% NH 4 CL was 12%; NH 4 OH was 21%.
  • the method for preparing nickel on the surface of die-cast aluminum parts and forming a surface aluminum nitride layer is
  • the processed die-cast aluminum parts are sealed, and the sealed die-cast aluminum parts are buried in a mixture of nickel nitride and carbon, heated to 380 ° C in a nitrogen atmosphere of 1 MPa, and kept for 2 hours, and then cooled to room temperature;
  • the mass ratio of nickel nitride to carbon is 1:10.
  • Alkaline electroless nickel plating solution calculated by weight percentage, consisting of:
  • NaCL12.6H 2 O is 9%; NiSO 4 .6H 2 O is 11%; NaHPO 2 .2H 2 O is 8%; (NH 4 ) 3 C 6 H 5 O 7 is 19%; complexing agent is 19% NH 4 CL is 12%; NH 4 OH is 22%.
  • the method for preparing nickel on the surface of die-cast aluminum parts and forming a surface aluminum nitride layer is
  • the processed die-cast aluminum parts are sealed, and the sealed die-cast aluminum parts are buried in a mixture of nickel nitride and carbon, heated to 360 ° C under a nitrogen atmosphere of 0.5 MPa, and kept for 1 hour, and then cooled to room temperature. ;
  • the mass ratio of nickel nitride to carbon is 1:8.
  • Alkaline electroless nickel plating solution calculated by weight percentage, consisting of:
  • NaCL12.6H 2 O is 8%; NiSO 4 .6H 2 O is 10.5%; NaHPO 2 .2H 2 O is 8.5%; (NH 4 ) 3 C 6 H 5 O 7 is 19.5%; complexing agent is 19.5% NH 4 CL was 12.5%; NH 4 OH was 21.5%.

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  • Engineering & Computer Science (AREA)
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Abstract

一种压铸铝零件表面处理工艺，即将经过喷砂处理的压铸铝零件使用氮化镍进行表面渗镍及形成表面氮化铝层处理，其中压铸铝零件还需进行镀镍前处理工序，将经过前处理工序后的压铸铝零件在碱性化学镀镍溶液内将压铸铝零件镀覆一层镀镍层，再使用拉丝机在镀镍层上拉出丝纹，并在拉出丝纹的压铸铝零件上电镀保护层；前述表面处理工艺中首先进行表面渗镍及形成表面氮化铝层处理，这样通过渗镍工艺将镍渗于压铸铝零件的空隙之间，然后再通过氮气与压铸铝零件表面的铝形成氮化铝保护层，该保护层即能够防止铝与氧气之间发生氧化反应，又能提高镀镍层与压铸铝表面的结合力。

Description

一种压铸铝零件表面处理工艺 技术领域
本发明属于金属表面处理技术领域，特别是指一种压铸铝零件表面处理工艺。
背景技术
铝及其合金虽然被广泛的应用，但是由于铝的电极电位较低，当在潮湿环境中与高电位金属接触时，极易产生接触腐蚀。另外铝合金在制造过程中，由于追求高的力学性能和其他方面的综合性能而添加各种合金元素，这些元素的存在使得铝合金内部化学成份和组织不均匀，再加上热处理和加工过程中残余应力的存在，使得铝合金材料在使用环境中极易造成微电池腐蚀。而且铝合金在使用环境中，不可避免地存在着潮湿空气，这些潮湿空气凝结在铝合金材料表面形成水膜，更为严重的是潮湿空气中存在一定含量的Cl-、SO2、H2S、CO2等物质，在这种情况下，铝合金材料更容易发生点蚀、晶间腐蚀、应力腐蚀等形式的破坏。
针对铝及铝合金材料的易腐蚀特性，对铝及铝合金的表面处理技术，以提高铝及铝合金材料的防腐蚀性能是本领域的重点课题，目前，型材铝合金阳极氧化技术和铬酸盐化学氧化技术得到广泛的应用，对于压铸铝合金零件，由于其形状复杂和合金元素含量高而不能采用阳极氧化，而铬酸盐化学氧化成本低、操作方便、耐蚀性能高而被广泛使用。
但是近年来，因为三价格对人类健康及环境存在潜在危害，而使用受到限制，为此，无铬化表面处理技术得到开发，现阶段，无机无铬处理方法主要是采用锆、钛、钴、钼、稀土等金属无机盐作为成膜溶液的主盐，在铝合金表面形成一层较薄的转化膜；有机膜处理方法是利用有机硅烷能够改善聚合物与无机材料之间的粘合力而在金属表面形成一层有机保护膜，但是有机膜的成膜时间长且成本高。
而且铝及铝合金材料在进行表面处理前处理后的表面易与空气中的氧进行反应，而影响后期的表面处理效果，现有技术通常是在铝及铝合金材料的表 面采用覆锌层，并且在后序的表面处理时，通过部分牺牲这一覆锌层来防止铝及铝合金表面的氧化并且提高与表面处理层的结合。
但是覆锌层在最后基本上是以废液的方式被排出，这不仅导致对环境的污染，而且提高铝及铝合金表面处理的成本。
发明内容
本发明的目的是提供一种压铸铝零件表面处理工艺，以解决压铸铝表面处理存在结合力不高及处理成本高的问题。
本发明是通过以下技术方案实现的：
一种压铸铝零件表面处理工艺，包括以下步骤：
1)将压铸铝零件经过喷砂处理；
2)将经过喷砂处理后的压铸铝零件使用氮化镍进行表面渗镍及形成表面氮化铝层处理；
3)将步骤2)的压铸铝零件进行镀镍前处理工序；
4)将经过前处理工序后的压铸铝零件在碱性化学镀镍溶液内将所述压铸铝零件镀覆一层镀镍层；
5)使用拉丝机在所述镀镍层上拉出丝纹；
6)在拉出丝纹的所述压铸铝零件上电镀保护层。
所述喷砂处理为陶瓷喷砂，压铸铝零件表面粗糙度控制在40-60μm。
所述压铸铝零件表面渗镍及形成表面氮化铝层的制备方法是，
将加工后的压铸铝零件封孔，并将封孔后的压铸铝零件埋于由氮化镍与碳混合物中，在0.3-1MPa氮气氛围下加热到350℃-380℃，并保温0.5-2小时，然后降至室温；
所述氮化镍与所述碳的质量比为1：10-1：5。
所述镀镍前处理工序至少包括清洗工序及酸洗工序，在所述酸洗工序后还包括碱液中和工序及去离子水冲洗工序。
所述清洗工序包括碱液除油工序、超声波清洗工序或碱液除油及超声波清洗工序。
所述碱性化学镀镍溶液，按重量百分比计算，其组成为：
Figure PCTCN2018080469-appb-000001
所述保护层为无铬保护层或含铬保护层。
本发明的有益效果是：
本技术方案的压铸铝表面处理工艺，在进行镀镍层之前，首先进行表面渗镍及形成表面氮化铝层处理，这样通过渗镍工艺将镍渗于压铸铝零件的空隙之间，然后再通过氮气与压铸铝零件表面的铝形成氮化铝保护层，该保护层即能够防止铝与氧气之间发生氧化反应，又能提高镀镍层与压铸铝表面的结合力，同时，避免了在压铸铝表面处理工艺中锌的使用，减少了处理成本。
具体实施方式
以下通过实施例来详细说明本发明的技术方案，以下的实施例仅是示例性的，仅能用来解释和说明本发明的技术方案，而不能解释为是对本发明技术方案的限制。
本技术方案提供一种压铸铝零件表面处理工艺，包括以下步骤：
1)将压铸铝零件经过喷砂处理；在本申请中，使用的陶瓷喷砂处理技术，并将压铸铝零件表面粗糙度控制在40-60μm。在本技术方案中，不使用其它喷砂技术的原因是，本申请使用的陶瓷为氧化铝陶瓷，以防止在进行喷砂过程中，因为压力的作用，会导致硅、铁等元素的渗入，而影响对压铸铝零件表面的最后处理效果，特别是影响镀镍层与压铸铝零件表面的结合力。
2)将经过喷砂处理后的压铸铝零件使用氮化镍进行表面渗镍及形成表面氮化铝层处理；
3)将步骤2)的压铸铝零件进行镀镍前处理工序；
4)将经过前处理工序后的压铸铝零件在碱性化学镀镍溶液内将压铸铝零 件镀覆一层镀镍层；将加工后的压铸铝零件封孔，并将封孔后的压铸铝零件埋于由氮化镍与碳混合物中，在0.3-1MPa氮气氛围下加热到350℃-380℃，并保温0.5-2小时，然后降至室温。
氮化镍与碳的质量比为1：10-1：5。
在本工序中，氮化镍在350℃-380℃会分解为氮气及金属镍，在此温度下，与压铸铝零件表面接触的金属镍会渗入压铸铝零件的表面，而在此温度下，碳不会渗入压铸铝零件表面也不会与压铸铝零件表面的铝发生反应生成碳化铝而影响后序处理。
通过在压铸铝零件表面的渗镍，其首先封闭压铸铝零件表面的孔隙，防止空气的进入，避免与氧气的接触，另一方面，渗镍层与压铸铝零件表面的结合度高，能够避免在使用电镀镍过程中，因为电镀时间短，镍层覆盖速度快而导致压铸铝零件表面的孔隙被镀镍层覆盖而不是填入，即在现有技术的镀镍层过程中，压铸铝零件表面的孔隙并不是被填补，而仅是覆盖，这样，在压铸铝零件表面在镀镍后的孔隙依然是存在的，并且，该孔隙有些会有电镀液中的水分子存在，这样在该孔隙处形成化学电池，而影响压铸铝零件的耐腐蚀性能。
本技术方案是通过渗入技术，在进行镀镍层前，通过渗入的方式，使得镍能够渗入到压铸铝零件的空隙中，填补了压铸铝零件的孔隙，这同时也是现有技术即使是覆锌层也解决不了压铸铝零件表面的孔隙问题，同时，也不需要使用覆锌层这一牺牲层的技术。
5)使用拉丝机在镀镍层上拉出丝纹；本技术方案是使用自动拉丝机在压铸铝零件的侧面镀镍层上拉上丝纹，以提高压铸铝零件的品质。
6)在拉出丝纹的压铸铝零件上电镀保护层。
镀镍前处理工序至少包括清洗工序及酸洗工序，在酸洗工序后还包括碱液中和工序及去离子水冲洗工序。
清洗工序包括碱液除油工序、超声波清洗工序或碱液除油及超声波清洗工序。在本技术方案中，镀镍前的前处理工序为现有技术，在此申请人不进行详细的说明，凡是能够适用于现有技术的前处理工序均可以在本技术方案中应用。
碱性化学镀镍溶液，按重量百分比计算，其组成为：
Figure PCTCN2018080469-appb-000002
Figure PCTCN2018080469-appb-000003
在本申请中，化学镀镍溶液的pH值为8.0-9.0。
保护层为无铬保护层或含铬保护层。在本申请的技术方案中，关键技术中在镀镍层前的渗镍处理技术及氮化铝层的形成，对于最后的保护层的技术为现有技术，可以根据需要使用现有技术中的无铬处理技术或有铬处理技术均可，并不影响本申请技术方案的实现。
在本申请的技术方案中，各实施例的区别分别为表面渗镍及表面氮化铝层的处理以及碱性化学镀镍溶液的不同。
实施例1
压铸铝零件表面渗镍及形成表面氮化铝层的制备方法是，
将加工后的压铸铝零件封孔，并将封孔后的压铸铝零件埋于由氮化镍与碳混合物中，在0.3MPa氮气氛围下加热到350℃，并保温0.5小时，然后降至室温；
氮化镍与碳的质量比为1：5。
碱性化学镀镍溶液，按重量百分比计算，其组成为：
NaCL12.6H 2O为8％；NiSO 4.6H 2O为10％；NaHPO 2.2H 2O为9％；(NH 4) 3C 6H 5O 7为20％；络合剂为20％；NH 4CL为12％；NH 4OH为21％。
实施例2
压铸铝零件表面渗镍及形成表面氮化铝层的制备方法是，
将加工后的压铸铝零件封孔，并将封孔后的压铸铝零件埋于由氮化镍与碳混合物中，在1MPa氮气氛围下加热到380℃，并保温2小时，然后降至室温；
氮化镍与碳的质量比为1：10。
碱性化学镀镍溶液，按重量百分比计算，其组成为：
NaCL12.6H 2O为9％；NiSO 4.6H 2O为11％；NaHPO 2.2H 2O为8％；(NH 4) 3C 6H 5O 7为19％；络合剂为19％；NH 4CL为12％；NH 4OH为22％。
实施例3
压铸铝零件表面渗镍及形成表面氮化铝层的制备方法是，
将加工后的压铸铝零件封孔，并将封孔后的压铸铝零件埋于由氮化镍与碳混合物中，在0.5MPa氮气氛围下加热到360℃，并保温1小时，然后降至室温；
氮化镍与碳的质量比为1：8。
碱性化学镀镍溶液，按重量百分比计算，其组成为：
NaCL12.6H 2O为8％；NiSO 4.6H 2O为10.5％；NaHPO 2.2H 2O为8.5％；(NH 4) 3C 6H 5O 7为19.5％；络合剂为19.5％；NH 4CL为12.5％；NH 4OH为21.5％。
尽管已经对本发明的技术方案进行了详细的描述，但是本领域的技术人员均清楚，通过对本技术方案进行的修改、替换及修饰等，均应当在本申请的保护范围之内。

Claims (7)

  1. 一种压铸铝零件表面处理工艺，其特征在于，包括以下步骤：
    1)将压铸铝零件经过喷砂处理；
    2)将经过喷砂处理后的压铸铝零件使用氮化镍进行表面渗镍及形成表面氮化铝层处理；
    3)将步骤2)的压铸铝零件进行镀镍前处理工序；
    4)将经过前处理工序后的压铸铝零件在碱性化学镀镍溶液内将所述压铸铝零件镀覆一层镀镍层；
    5)使用拉丝机在所述镀镍层上拉出丝纹；
    6)在拉出丝纹的所述压铸铝零件上电镀保护层。
  2. 根据权利要求1所述的压铸铝零件表面处理工艺，其特征在于，所述喷砂处理为陶瓷喷砂，压铸铝零件表面粗糙度控制在40-60μm。
  3. 根据权利要求1所述的压铸铝零件表面处理工艺，其特征在于，所述压铸铝零件表面渗镍及形成表面氮化铝层的制备方法是，
    将加工后的压铸铝零件封孔，并将封孔后的压铸铝零件埋于由氮化镍与碳混合物中，在0.3-1MPa氮气氛围下加热到350℃-380℃，并保温0.5-2小时，然后降至室温；
    所述氮化镍与所述碳的质量比为1：10-1：5。
  4. 根据权利要求1所述的压铸铝零件表面处理工艺，其特征在于，所述镀镍前处理工序至少包括清洗工序及酸洗工序，在所述酸洗工序后还包括碱液中和工序及去离子水冲洗工序。
  5. 根据权利要求4所述的压铸铝零件表面处理工艺，其特征在于，所述清洗工序包括碱液除油工序、超声波清洗工序或碱液除油及超声波清洗工序。
  6. 根据权利要求1所述的压铸铝零件表面处理工艺，其特征在于，所述碱性化学镀镍溶液，按重量百分比计算，其组成为：
    Figure PCTCN2018080469-appb-100001
    Figure PCTCN2018080469-appb-100002
  7. 根据权利要求1所述的压铸铝零件表面处理工艺，其特征在于，所述保护层为无铬保护层或含铬保护层。
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